Contents lists available at ScienceDirect Clinical Biomechanics journal homepage: www.elsevier.com/locate/clinbiomech A comprehensive finite element model of surgical treatment for cervical myelopathy ☆,☆☆ Kirsten E. Stoner a , Kingsley O. Abode-Iyamah b , Douglas C. Fredericks c , Stephanus Viljoen d , Matthew A. Howard e , Nicole M. Grosland a,c, ⁎ a Biomedical Engineering, The University of Iowa, USA b Department of Neurosurgery, Mayo Clinic, Jacksonville, FL, USA c Department of Orthopedics and Rehabilitation, The University of Iowa Hospitals and Clinics, USA d Department of Neurosurgery, The Ohio State University Wexner Medical Center, USA e Department of Neurosurgery, The University of Iowa Hospitals and Clinics, USA ARTICLE INFO Keywords: Laminectomy Laminoplasty Anterior cervical discectomy and fusion Spinal cord Cervical spine Finite element model Cervical myelopathy ABSTRACT Background: Cervical myelopathy is a common and debilitating chronic spinal cord dysfunction. Treatment includes anterior and/or posterior surgical intervention to decompress the spinal cord and stabilize the spine, but no consensus has been made as to the preferable surgical intervention. The objective of this study was to develop an finite element model of the healthy and myelopathic C2-T1 cervical spine and common anterior and posterior decompression techniques to determine how spinal cord stress and strain is altered in healthy and diseased states. Methods: A finite element model of the C2-T1 cervical spine, spinal cord, pia, dura, cerebral spinal fluid, and neural ligaments was developed and validated against in vivo human displacement data. To model cervical myelopathy, disc herniation and osteophytes were created at the C4-C6 levels. Three common surgical inter- ventions were then incorporated at these levels. Findings: The finite element model accurately predicted healthy and myelopathic spinal cord displacement compared to motions observed in vivo. Spinal cord strain increased during extension in the cervical myelopathy finite element model. All surgical techniques affected spinal cord stress and strain. Specifically, adjacent levels had increased stress and strain, especially in the anterior cervical discectomy and fusion case. Interpretations: This model is the first biomechanically validated, finite element model of the healthy and myelopathic C2-T1 cervical spine and spinal cord which predicts spinal cord displacement, stress, and strain during physiologic motion. Our findings show surgical intervention can cause increased strain in the adjacent levels of the spinal cord which is particularly worse following anterior cervical discectomy and fusion. 1. Introduction The spinal cord is one of the most important organs for humans and animals as it is responsible for transferring all vital signals for life from the brain to the rest of the body (Boron and Boulpaep, 2008). However, its function is highly susceptible to mechanical stimuli, as both direct strain and spinal positioning can negatively affect neuronal signaling (Fujita and Yamamoto, 1989; Morishita et al., 2013). Cervical myelo- pathy (CM), a common form of spinal cord dysfunction, is attributed to chronic compression of the spinal cord from disc herniation or ligamentous hypertrophy. This compression can increase during daily motion, exacerbating CM symptoms which include upper extremity numbness, loss of dexterity, gait disturbances, and potentially irrever- sible neurological deficit (Beattie and Manley, 2011; Hashizume et al., 1984; Hayashi et al., 1987; Ichihara et al., 2003; Rhee et al., 2009; Stookey, 1928). The current accepted treatment for CM is surgical intervention where the spinal cord is decompressed, and the spine is stabilized. One of two surgical approaches is used: an anterior approach or a posterior approach. There has been much debate as to which surgical approach is https://doi.org/10.1016/j.clinbiomech.2020.02.009 Received 11 October 2019; Accepted 13 February 2020 ☆ This work was originally presented in part in the doctoral thesis of Kirsten E. Stoner. ☆☆ This work was funded in part by grant #1U49CE002108-03 of the National Center for Injury Prevention and Control/CDC and The University of Iowa Deans Graduate Research Fellowship. ⁎ Corresponding author. E-mail addresses: kirsten.stoner@gmail.com (K.E. Stoner), nicole-grosland@uiowa.edu (N.M. Grosland). Clinical Biomechanics 74 (2020) 79–86 0268-0033/ © 2020 Elsevier Ltd. All rights reserved. T